Unfortunately time wasn't on my side and I was in a hurry to head out so I didn't look to hard. I do not recall seeing any pitting on the surface of that cylinder though but again I didn't look very hard. My focus was purely on getting it out and flooding with a penetrating oil.

I know for certain the middle cylinder looked fine. Next time I'm at the boat I'll be spending a bit more time cleaning them up a bit more in attempt to completely remove any remaining gunk particulate and resoaking. I'll also check for more evidence of pitting

Thanks!! That seems like an effective method from what I'm reading! I'll have to give this a try!

How fast does the acetone evaporate out of the mixture?

Not as quickly as you would think.. In your situation the ATF is the more important part. Even ATF by itself seems to work better then the true "penetrating oils". The Acetone just gets the creep started and reduces the wait time.

Plus the ATF has detergents that will remove some of the gunk and carbon.

Not as quickly as you would think.. In your situation the ATF is the more important part. Even ATF by itself seems to work better then the true "penetrating oils". The Acetone just gets the creep started and reduces the wait time.

Plus the ATF has detergents that will remove some of the gunk and carbon.

Very interesting! Will need to pick some up next time I'm at the store!

As for pitting, even if its present, wouldn't I be able to hone/bore out the cylinder or put in a sleeve?

If it turns out that the engine is completely unsalvagable, all is not lost. You may be able to find a used Shibaura block that you can bolt the marine stuff to. The Perkins M series engines are based on Shibaura blocks. Complete engines come up on e-bay from time to time for MUCH less than rebuilding (like $2000+400 shipping). These blocks were used in tractors, chippers, pumps and generators. Google and Ebay are your friend, search for 103-6 or 103.6 perkins.

Not as quickly as you would think.. In your situation the ATF is the more important part. Even ATF by itself seems to work better then the true "penetrating oils". The Acetone just gets the creep started and reduces the wait time.

Plus the ATF has detergents that will remove some of the gunk and carbon.

I've always used atf to final clean engines and heads before assembly. ATF on a clean white rag will lift and show any dirt, grit or honing grit. It's amazing how some people are prepared to assemble an engine full of grit and then wonder why they have a smoky result.

If the piston tops and bores are pit free you might just get away with a lightweight topend rebuild. You need to use lightweight magnification, not the mark one eyeball, to look for pitting though.

I thought you were just trying to get it running well. If you are up for taking the engine all apart you can probably fix just about anything.

Good point. I am just trying to get it running

I don't necessarily want to pull it all apart, however if that's required to get it to run again, than I shall. If I can get the pistons to break free and everything else turning over I'll try to fire her up and run her as is and them go from there

Well ive gotten 5 of the 6 valves on the cylinder head freely moving! They were all frozen shut. One still is but maybe a couple more days of soaking will change that or a soak in atf/acetone mixture when I get around to buying some atf will solve that.

Well, starting from the beginning, that fluffy white stuff on top of the pistons is oxidized aluminum, probably from seawater, but could be from condensation in an engine that has been sitting for a long time. My guess is that even after you get the engine turning the rings are going to be corroded into the ring grooves, which will necessitate pulling the pistons out and unsticking the rings at a minimum, and probably replacing the pistons.

On a diesel engine the cylinder wall surface is crucial for the engine to make full power, any pitting is bad, though sometimes an engine will run reasonably well with minor imperfections. Since the cylinders are cast into the block generally you just get the block bored and honed. I'm pretty sure pistons are available in .25 and .5 mm oversize.

The good new is that these engines are used in a wide variety of applications, the important part is identifying which one you have. I was under the impression that the m20 was an ISM/Perkins 103-07, but I could be wrong. The actual engine number, be it 103-06 or 103-07 may be cast into the side of the block, a sure fire way is to measure the piston diameter, the 103-06 is 64 mm, the 103-07 is 67mm.

A lot of these engines, in variety of sizes were used in AC units for 18 wheeler reefer units and medium big lawn mowers, parts are everywhere and are available in original and aftermarket. The supply seems a little confusing, I suppose because of the many applications, but a few phone calls to different parts suppliers should eventually get you in touch with a knowledgeable person. Perkins prices are generally reasonable, try and stay away from strictly marine suppliers. As an example my first search for '103-07 piston' turned up a piston for 76.00 US